1. Field of the Invention
This invention relates to a composite plastic shading member which may be used for a curtain for camera shutters and the like.
2. Description of the Prior Art
Heretofore, there have been proposed plastic curtains for shading members of light weight and high rigidity for use as high speed electromagnetic driving shutters in cameras. For example, Japanese Patent Application Laid-open No. 141625/1982 discloses a shutter curtain constituted of a sheet composed of a plastic material filled with a reinforcing material such as glass cloth, carbon fiber, polyester fiber, asbestos, paper and the like, the surface of the sheet being covered with an organic coating film having a lubricating property. In addition, Japanese Patent Application Laid-open No. 61827/1984 discloses a shading curtain having a hollow portion and surface layers at least one of which is formed by using a resin reinforced with carbon fibers (by way of prepreg sheet).
However, in the case of the former shutter curtain, the type and amount of the filling material are limited and it is difficult to disperse uniformly the filling material and therefore, it is difficult to obtain a curtain of thin thickness, light weight and high rigidity. Further, in the case of the latter curtain, it requires much labor to fabricate a composite member having a hollow portion by using a prepreg laminate sheet of a continuous carbon fiber, and therefore, from an industrial point of view, the productivity and cost are disadvantageous. On the contrary, it is a simple method for producing a curtain to use a prepreg laminate sheet of carbon fiber alone. However, upon fabrication of the prepreg, a carbon fiber flux is loosened as much as possible and carbon fibers are arranged in one direction to obtain a thin prepreg impregnated with a half-cured resin. However, when the thickness is made as thin as about 50-60 .mu.m, the gap between fiber fluxes deviates. In particular, the fiber fluxes get out of position due to lowered viscosity of resin when the prepreg is heated and cured under pressure. Therefore, it is difficult to keep the bending rigidity uniform and the sheet-like shaped article after being cured is liable to be torn in the arranged direction, and therefore, it is difficult to use the carbon fiber reinforced resin sheet alone as a shading member moving at a high speed.